Atrazine Incorporation and Soil Erosion – Balancing Competing Water Quality Concerns for Claypan and Restrictive Layer Soils R. N. Lerch, C. M. Harbourt, R. R. Broz, and T. J. Thevary ARS Field 1 near Centralia, MO Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Background - Claypan Soils  Central Claypan Areas o Major Land Resource Area 113 o Encompasses 33,000 km 2 in MO and IL  Claypan Characteristics o Smectitic mineralogy (high shrink- swell potential) 40-60% clay content o Near surface feature (0-60 cm) o K sat <1  m/s o Claypan is an extreme form of an argillic horizon  Vulnerable to contaminant transport in surface runoff Soil-applied herbicides Soil erosion Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Rationale  A major challenge associated with claypan soils is the need to develop cropping systems that concurrently facilitate incorporation of herbicides to reduce their transport in surface runoff, but maintain sufficient crop residue cover to control soil erosion (Lerch et al., 2008).  Conflicting Goals o No-till precludes the incorporation of herbicides. o Incorporation increases soil erosion  Conflicting goals require a balanced approach rather than managing for one problem at the expense of another o Herbicide application methods must be found that can incorporate soil-applied herbicides and maintain greater residue cover than commonly used reduced tillage systems, such as disc harrow or field cultivator. No-Till Treatment; Simulation #3 Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Objective  Compare the effect of 3 tillage systems on sediment and atrazine transport in surface runoff o Tillage treatments Phillips Harrow (Harrow) No-Till Field Cultivator (Minimum-Till) o Data Collected Hydrologic Time to initiation of runoff, instantaneous discharge, and total volume Water Quality Suspended sediment (SS) concentration and load Atrazine concentration (by ELISA) and load Agronomic Residue cover, weed cover, corn yield Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Phillips Harrow Roller harrow Seedbed preparation Maintains greater residue cover than disc harrows or field cultivators Incorporate herbicides (or fertilizer) to ~5cm depth Working speeds up to 12 mph Low horsepower requirements ( hp) High working capacity - >40 ac/hr for the 45’ wide implement One-pass spraying and incorporation - can be equipped with spray nozzles and tanks Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Experimental Design Site Description  Site located at the University of Missouri, Bradford Research and Extension Center  Soil Series o Leonard Silt Loam, ~2% slope o Common backslope claypan soil o Managed as no-till corn- soybean rotation for last 15 years (soybean in 2010).  Experiment conducted from 6/6 – 6/10/2011 o No natural rainfall occurred! Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Experimental Design Plot Layout Each treatment was replicated six times in two sets of three plots. S N Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

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Experimental Design Tillage Treatments  Phillips Harrow o Tilled with a disc harrow to 10 cm depth one week prior to experiment Intended to represent the expected residue cover from a conventionally managed corn-soybean rotation o Atrazine applied at 2 lbs/ac, then incorporated with 2-passes to 3-5 cm depth. o Operating speed was 8-9 mph (13-15 km/h).  No-Till o Atrazine applied at 2 lbs/ac  Field Cultivator o Disc harrow one week prior to experiment o Atrazine applied at 2 lbs/ac, then incorporated with 2-passes to 10 cm depth.  All treatments o Whole plot areas sprayed with Bicep (2 lbs/ac atrazine; 1.6 lbs/ac metolachlor) following rainfall simulations o Corn planted on June 16, 2011 Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Experimental Design Plot Set-up  Site selection within the bulk plot based on minimizing side slope  0.25% or less  Slopes o Harrow – 2.1% o No-Till – 2.6% o Minimum-Till – 2.3%  Border steel installed to ~15 cm depth after herbicide spraying  Down slope section constructed with a diversion wall and metal gutter  Gutter attached to a PVC pipe to divert runoff to the sample bucket Diversion wall Gutter 5 cm PVC pipe Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

 Runoff was generated using the HMWRS-001 rainfall simulator, designed by Waterborne Environmental, Inc. o Rainfall rate target for runoff collection was 27 mm/hr o Rained on three sub-plots at a time o Field operations were performed in the following sequence: Plots brought to saturation 48 hours before runoff collection Plots sprayed hours before runoff collection Experimental Design Experimental Design Rainfall Simulation Photo courtesy of Waterborne Environmental, Inc. Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Experimental Design Experimental Design Runoff Collection  Instantaneous discharge o Determined by recording the time to fill a 15-L bucket o Buckets composited in a 500-L plastic barrel Provided total runoff volume and composite samples for atrazine and suspended sediment  Runoff Samples o Collected at 1, 5, 10, 15, 20, 30, 50, 70, and 90 minutes following the initiation of runoff. o Samples analyzed for SS and atrazine concentration Photo courtesy of Waterborne Environmental, Inc. Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Experimental Design Experimental Design Residue Cover and Weed Control  Residue cover o Assessed on every runoff plot and 6 randomly chosen areas within the bulk plots Digital images acquired on 1 m 2 areas using square borders placed over the soil surface  Weed control o Six randomly chosen 1 m 2 areas within the bulk plot (runoff plots excluded) were digitally photographed approximately two weeks after Bicep application and corn planting.  Images were analyzed for the fraction of the area covered by residue or weeds Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Results Hydrology Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Results Hydrology

Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Results Erosion – SS Concentration Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Results Erosion – SS Loads Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Results Atrazine Concentrations Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Results Atrazine Concentrations Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Results Atrazine Loads Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Summary and Conclusions  Hydrology o No treatment differences in mean discharge or total runoff volume o No-till significantly increased normalized runoff volume and decreased time to initiation of runoff  Erosion o SS concentration: No-till < Harrow < Minimum-Till o SS load: No-till = Harrow < Minimum-Till  Atrazine o Concentration: Minimum-Till < Harrow < No-Till o Load: Minimum-Till = Harrow < No-Till  Supported other studies on claypan soils (Ghidey et al., 2005 and 2010) : o Effectiveness of incorporation for reducing atrazine transport in runoff o No-till does not reduce runoff volume and greatly increases atrazine losses on claypan soils  Roller harrow achieved the needed balance by controlling both erosion and atrazine losses Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

Benefits of Roller Harrows  Available tillage implement that is relatively low cost ($20-$40k)  Could readily replace disc harrows or field cultivators commonly used for seedbed preparation in corn production systems within the Central Claypan Areas  Improve sustainability of crop production by controlling erosion  Maintains farmer profitability  Improve the region’s two most persistent water quality problems by simultaneously managing the trade-off between erosion control and atrazine transport in runoff  Can be recommended as an atrazine BMP for claypan and restrictive layer soils!! Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO

 Syngenta Corp. for the funding, and proposal review and field work assistance  Waterborne Environmental, Inc. field crew  USDA-ARS field crew  Kristi Perry and University Extension  Todd Hensiek, Kane Holloway, and Tim McClintock for the research on the roller harrow as part of their ASM capstone class (2009) Acknowledgments Minimum-Till Treatment; Simulation #5 Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, October 2012, Columbia, MO